package com.xiaoman.keep_system.shiro;

import com.xiaoman.keep_system.config.UserContext;
import com.xiaoman.keep_system.exception.GlobleException;
import com.xiaoman.keep_system.pojo.po.Customer;
import com.xiaoman.keep_system.result.CodeMsg;
import com.xiaoman.keep_system.service.LoginService;
import com.xiaoman.keep_system.utils.JWTUtil;
import org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Component
public class JWTFilter extends BasicHttpAuthenticationFilter {

    @Resource
    private LoginService loginService;

    private static JWTFilter jwtFilter;//关键一：将自己作为静态私有变量引入，使其在springmvc初始化前被创建

    @PostConstruct      //关键二：通过@PostConstruct和@PreDestroy 方法实现初始化和销毁bean之前进行的操作
    public void init(){
        jwtFilter = this;
        jwtFilter.loginService = this.loginService;   //初始化时将已静态化的userService实例化
    }

    private Logger LOGGER = LoggerFactory.getLogger(this.getClass());

    /**
     * 判断用户是否想要登入。
     * 检测header里面是否包含Authorization字段即可
     */
    @Override
    protected boolean isLoginAttempt(ServletRequest request, ServletResponse response) {
        HttpServletRequest req = (HttpServletRequest) request;
        String authorization = req.getHeader("Authorization");
        return authorization != null;
    }

    /**
     *
     */
    @Override
    protected boolean executeLogin(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        String authorization = httpServletRequest.getHeader("Authorization");

        String userStr = new JWTUtil().getUsername(authorization);
        if (userStr == null){
            throw new GlobleException(CodeMsg.NOT_LOGIN);
        }
        Customer customer = jwtFilter.loginService.getCusByUsername(userStr);//关键三：使用jwtFilter.userService的方式使用
        System.out.println(customer.toString());
        UserContext.setUser(customer);

        JWTToken token = new JWTToken(authorization);
        // 提交给realm进行登入，如果错误他会抛出异常并被捕获
        try {
            getSubject(request, response).login(token);
        } catch (Exception e){
            e.printStackTrace();
        }
        // 如果没有抛出异常则代表登入成功，返回true
        return true;
    }

    /**
     * 这里我们详细说明下为什么最终返回的都是true，即允许访问
     * 例如我们提供一个地址 GET /article
     * 登入用户和游客看到的内容是不同的
     * 如果在这里返回了false，请求会被直接拦截，用户看不到任何东西
     * 所以我们在这里返回true，Controller中可以通过 subject.isAuthenticated() 来判断用户是否登入
     * 如果有些资源只有登入用户才能访问，我们只需要在方法上面加上 @RequiresAuthentication 注解即可
     * 但是这样做有一个缺点，就是不能够对GET,POST等请求进行分别过滤鉴权(因为我们重写了官方的方法)，但实际上对应用影响不大
     */
    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        if (isLoginAttempt(request, response)) {
            try {
                executeLogin(request, response);
            } catch (Exception e) {
                e.printStackTrace();
//                response401(request, response);
            }
        }
        return true;
    }

    /**
     * 对跨域提供支持
     */

    @Override
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
        httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,PUT,DELETE");
        httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));
        // 跨域时会首先发送一个option请求，这里我们给option请求直接返回正常状态
        if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {
            httpServletResponse.setStatus(HttpStatus.OK.value());
            return false;
        }
        return super.preHandle(request, response);
    }

    /**
     * 将非法请求跳转到 /401
     */
    private void response401(ServletRequest req, ServletResponse resp) {
        try {
            HttpServletResponse httpServletResponse = (HttpServletResponse) resp;
            httpServletResponse.sendRedirect("/401");
        } catch (IOException e) {
            LOGGER.error(e.getMessage());
        }
    }
}
